Minimally invasive surgery is becoming the preferred technique for accessing internal organs and systems in an ever increasing number of procedures. Its advantages are manifold. For example, recovery times are greatly decreased due to smaller incisions and less damage to internal structures while gaining access to the procedure site. Also, the risk of post-operative infection is somewhat reduced as the internal tissues are less exposed to non-sterile environments. In addition, the procedure is often simplified and expedited due to the lack of complex incisions and post-procedure suturing of large incisions.
Typically, in minimally invasive procedures, instruments are inserted into the body through steerable catheters that are initially inserted and brought adjacent to the affected organ or other procedure site. However, standard catheters do not stabilize the instrument in place while it is being used by the surgeon. Similarly, standard catheters can only be coarsely steered and are not generally capable of following a serpentine path.
Some specialized mechanisms for stabilizing particular instruments have been devised for procedures that require a close and immobile relationship between the instrument and the tissue being operated upon. For example, Bertolero et al., U.S. Pat. No. 6,849,075 teaches a cardiac ablation device that employs a plurality vacuum orifices to hold an ablation electrode in position on the heart. However, this reference does not provide a mechanism to move the electrode along a serpentine path on the heart or other organ, as may be required in certain procedures, most notably cardiac ablation, as described below. Likewise, there is no mechanism in Bertolero to bring, for example, a microwave ablation catheter into selective contact with heart tissue, as may be required for effective ablation.
An alternate approach suggested for transporting and positioning minimally invasive surgical instruments inside the body is taught by Riviere, et al. in Published U.S. patent application Ser. No. 10/982,670, using a walking robot. The robot comprises two pedestals connected by a spring. The distal pedestal includes a tool, typically a scope for viewing the affected area. The foot of each pedestal has vacuum orifices, with a separate vacuum line running to each pedestal. A pair of pull wires is connected to each pedestal, allowing control of the relative position between the distal pedestal and the proximal pedestal. By properly sequencing the application of vacuum and the tension on the pull wires, a surgeon can cause the robot to “inchworm” across the surface of an organ. Surgical instruments are attached to the front of the distal pedestal.
The Riviere robot employs a large vacuum region that interfaces best with flat organ tissue that is reasonably resilient. Under certain conditions its hold down could become dislodged or allow lateral slippage of the corresponding tool—particularly where the tissue surface is non-flat or roughened. To remedy such slippage, the vacuum applied to each pedestal may be increased. However, under other conditions tissue could be damaged by too intense local vacuum.
Moreover, these and other available devices lack the ability to perform more complex procedures, such as drug delivery, dissection and biopsy. Accordingly, it is highly desirable to provide improved mechanisms and devices for minimally invasive surgical procedures that afford improved function as well as superior mobility, immobilization once positioned, and control of an ablation device or other attached tool.